Environmental geochemistry of mineral deposits

Abstract

This work consists of a bibliographic review of the most relevant aspects to consider when carrying out an Environmental Geochemical evaluation of mineral deposits. Under the understanding that mineral deposits are a key piece for the social, industrial, technological and economic development of the World. Generally, when the deposits are exploited, they are directly associated with the contamination of water and soil, so it is essential to know their origin, composition and their possible impact on the environment, either naturally or induced.
Through Environmental Geochemistry, it is possible to determine the geological and chemical processes that release and/or control contaminants in the environment associated with mineral deposits. Particularly when the constituent metals and minerals are dispersed in the earth's crust by weathering and erosion in waters, soils and sediments of their adjacent environment.
The alteration of the geochemical environment that generated the mineral deposits, naturally or artificially, associated with the interaction of water and air, causes them to experience changes, weathering them and releasing their constituents. The released minerals interact with water, wind, sediments, soil, organic matter, rocks and minerals, generating chemical processes such as adsorption, precipitation, dissolution, speciation and complex formation, which will govern the mobility and/or inhibition of potentially toxic metals. for living beings.
At mining sites, the main pathway by which heavy metals are released is acid drainage, characterized by low pH values ​​and high metal concentrations. In tailings dams, the mobility of metals is much higher, due to particle size, high pyrite concentration and low carbonate content. Tailings deposits have their own characteristics, depending on the following parameters: nature of the exploitation, associated minerals, grain size, climate and bacterial action.